Abstract

We report on a simple but highly efficient source of polarization-entangled photon pairs at nondegenerate wavelengths. The fully collinear configuration of the source enables very high coupling efficiency into a single optical mode and allows the use of long nonlinear crystals. With optimized dispersion compensation, it is possible to use a free-running laser diode as pump source and to reach an entanglement fidelity of 99.4% at rates as high as of pump power.

Received 11 January 2008Accepted 18 April 2008Published online 28 May 2008

Acknowledgments:

The authors thank Y. Nazirizadeh for his assistance in the early stages of the project. This work was supported by Deutsche Forschungsgemeinschaft through the DFG-Cluster of Excellence MAP, by the DAAD-PPP Croatia program, and by the EU-projects QAP and SECOQC.